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Author Topic: What can Destroy DNA & Maggots can contain human DNA  (Read 11388 times)
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Monkey All Star Jr.
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« on: September 06, 2008, 01:29:29 PM »

Bacteria that Cause Food Poisoning Contain Toxins That Destroy DNA, a Yale Study Shows
New Haven, Conn. — Protein toxins found in bacteria that are the most common culprit in food poisoning attack and destroy DNA, a study by Yale researchers shows.

Bleach will very effectively destroy DNA," Peer said.

Most professional villains already know that a dilute solution of household bleach or hydrogen peroxide will destroy the DNA molecules within most types of trace evidence left at a crime scene.
« Last Edit: November 07, 2008, 12:50:16 PM by Blonde » Logged

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Monkey All Star Jr.
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« Reply #1 on: September 13, 2008, 10:52:19 AM »

The Dangers of Mixing Bleach and Ammonia

Often, one looks at a bottle of bleach and wonders, 'Why shouldn't this be mixed with ammonia?' If you know how dangerous chlorine gas is to humans (it was used as a chemical weapon during World War I and later by Nazi Germany in World War II), this will be very apparent. This entry will tell of a few reactions that can occur when bleach and ammonia are mixed in various proportions - the release of chlorine gas is just one of these. In the following sections, the header will be the name of the most dangerous compound produced in the reaction shown. Please, do not try any of this at home.

Chlorine Gas (Cl2)

That warning is there to protect you. Household bleach has a chemical formula of NaOCl - that is, one atom each of sodium, oxygen, and chlorine. Its chemical name, for the curious, is sodium hypochlorite. Ammonia has a chemical formula of NH3, that is, one atom of nitrogen and three atoms of hydrogen. When these two compounds are combined, the following reaction takes place:

2(parts)NaOCl + 2NH3 --> 2NaONH3 + Cl2.

Do you see that Cl2 on the right hand side there? This means one part chlorine gas, made up of diatomic (two atom) molecules. It also means that the chlorine gas has been liberated from the bleach, and is quite capable of causing you harm when inhaled!

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Monkey All Star Jr.
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« Reply #2 on: November 07, 2008, 12:49:13 PM »

Flies and maggots also provide an approximate time of death, very useful for cases where the body has been long dead. Only certain insects will feed and lay eggs on a dead corpse and forensic entomologists study these insects, their larvae cycles and thereafter can determine whether a body has been dead for just one day or up to 3 or 4 weeks.
Time Physical Appearance of Body Insects Present at that Stage
0-3 days 0-3 days Proteins and carbohydrates in the deceased body begin to break down. Blowflies e.g. Bluebottle flies, Syrphidae flies
4-7 days Body is starting to decay and causes the abdomen to inflate because of the gases inside. Fly larvae and beetle e.g. Rove Beetles
8-18 days 8-18 days Decay is well and truly setting in; the abdomen wall begins to break down. Ants, cockroaches, beetles and flies
19-30 days The decaying body enters a stage know as 'post-decay'; in wet, humid conditions, the body is sticky and wet; in hot dry conditions, the body is dried out. Beetles and mites e.g. Springtail beetle, Acari, Nematocera (present only during the winter months), Brachycera
31 and over days The bones, skin and hair that remain no longer give off a powerful stench and smell just like the soil surrounding it.

Decay can also determine how long a person has been dead for and in Tennessee, a special research area has been set up to study exactly how and why bodies decay. The research farm, known as The Body Farm, was established in 1981 by Bill Bass, a professor of forensic anthropology. By having decaying bodies readily available to study, Bass and his students discovered a number of factors contributing to body decay. Some things they discovered include that flies and maggots will turn a body in to a skeleton in under two weeks in warmer weather and the face will always rot first because maggots prefer wet places. He has also observed how fast bodies decay when submerged in water, stored in the boot of a car, or wrapped in plastic and that when a person's head is burnt, that the skull reaches boiling point very quickly, causing the skull to explode. If the person head doesn't explode, it means that the victim may have been shot in the head, allowing the steam to escape.

How do you figure out how old a maggot is?

Well, you need to know a few basic things first:

1. What species of fly the maggot is (maggots are fly larvae).

2. What kind of weather (especially temperature) has the body been in lately (the environment influences how fast maggots grow).

3. How long the maggot is, as maggots get longer with age.

Once you have the basic info, you compare it to previous research. For example, if you find a maggot from a body is the species Calliphora vicina, and the body has been indoors at 21oC, and the maggot is 6 mm long, then previous research suggests the maggot is at least 2 days old. Therefore, the person has likely been dead for at least two days.

So, how do you find out what species of fly a maggot is?

Most forensic entomologists take the maggots from the body and raise them in jars with rotting meat until they grow up to become adult flies. A forensic entomologist can then use characteristics such as the number of veins in a fly’s wings and the shape of male genitalia to determine what species of fly it is. They have to raise the maggots up to adult flies because, even to an expert, most species of maggot look the same.

Genetics is changing how forensic entomologists identify maggot species.

Every species of fly has different DNA. Therefore, reading the genetic sequence of a maggot’s DNA, will tell you the species of fly. This has several advantages over the traditional method of raising maggots to adult flies:

Speed: Grinding up a maggot and analyzing its DNA takes only a day or two instead of days to weeks to raise a maggot to an adult fly. The faster police can get an estimate of how long a person has been dead, the more precisely they can focus their investigation.

Availability: DNA sequence-reading facilities are common, while fly experts are rare and often far away.

Specimen types: You can get DNA from dead maggots, or parts broken off maggots in shipment from the police, but in order to raise a maggot to adulthood it needs to be alive and healthy.

Courtroom evidence: The type of evidence courts are most likely to accept is the kind that is based on numbers and probabilities as opposed to an expert’s personal opinion. Using DNA to determine what species a maggot is will result in a percent probability
estimate that can be presented in court (e.g., “The maggot had a 99.3% probability of being the species Calliphora vicina based on its DNA sequence”), while using the anatomy of an adult fly does not provide any probability estimate.

Looking at the bugs on a corpse may also tell you if the body has been moved or disturbed after death. Different bugs are found in different surroundings (compare the bush with the beach for example), so if a body were moved after a crime, the insects on the body wouldn't match up with what you'd expect in those surroundings. Also, moving or disturbing the body after the bugs have arrived can mess up the insects' life cycles, and forensic entomologists can pick this up too.

Other useful info that maggots can provide include whether or not there were any wounds on a body (something that's tricky to determine once decomposition sets in), or whether the person was under the influence of drugs before death (the maggots 'bioaccumulate' or collect the drugs from the flesh that they've eaten, so drugs can be identified even after the body has mostly decomposed).

Insects can also be used, in some cases, to determine the general location of a murder and even to help identify the victim. If, for example, a corpse is found in New England but forensic experts determine that larvae retrieved from the corpse are from a species of beetle that exists only in the South, investigators know two things—that the body has been moved from a Southern location, and that it could be that of a missing person last seen in a Southern state.

Just Looking for the Truth
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